The present invention relates to an improved chemical process for the removal of an allyl or allyloxycarbonyl group from an allyl or allyloxycarbonyl group protected compound (such as an allylic ester, carbonate, carbamate, O-allyl derivatives or N-allyl derivatives). This process comprises contacting the allyl or allyloxycarbonyl group protected compound with a sulfinic acid compound, in the presence of a palladium catalyst in a reaction-inert solvent.
Allyl groups have been frequently used as protecting groups for a carboxyl group or the like in the synthesis of beta-lactam antibiotics. The advantages of the use of the allyl groups in the synthesis of beta-lactam antibiotics have been reported by S. W. McCombie et al. [J. Org. Chem., 47, 587 (1982)]. The removal of an allyl group from an allylic ester or the like has been reported in several literature and patent gazettes.
Japanese Patent Application Publication No. S60-9730 (U.S. Pat. No. 4,314,942) discloses a process for the removal of an allyl group in an allylic ester or an allyloxycarbonyl group in an allylic carbonate or carbamate by reaction with 2-ethylhexanoic acid or an alkali metal salt thereof in the presence of an organic-soluble palladium complex catalyst.
Japanese Patent Application Laid-Open No. H03-130293 (EP 410727A1) describes a process for removing an allyl group from a penem compound by reaction with a cyclic 1,3-diketone compound, such as dimedone, or its alkali metal enolate. Japanese Patent Application Laid-Open No. H04-41489 discloses a similar process using an alkali metal salt of a carboxylic acid having 1 to 4 carbon atoms.
However, according to the above conventional methods, the yield of the final reaction product was not always high. For example, in the conventional methods, the activity of catalyst was lowered by using crude raw materials, and the yield was lowered in the treatment of compound which is sensitive to the basic condition of the protecting group.
On the other hand, O-allylethers and N-allyl derivatives of amino group are stable in a nucleophilic reaction and electrophilic reaction. Thus, protection of a hydroxy group by using O-allylether or protection of an amino group by using N-allyl derivative is considered useful in a variety of synthesis for biologically active compounds. However the allyl protection has not been frequently used in this field, because deprotection of the allyl group from O-allylether or N-allyl derivative could not be done under mild conditions.
Japanese Patent Application Publication No. H02-262542 (USP409100019) discloses a process for the removal of an allyl group in a N-allylaniline in the presence of palladium or cupper complex catalyst. In this process, however, considerably severe condition are required.
Therefore, it would be desired if a method of removing an allyl group or the like from a variety of compounds having an allyl group or the like such as an allylic ester, carbonate, carbamate, O-allyl derivatives or N-allyl derivatives were provided, with excellent yield, in a highly chemoselective manner without affecting any rest of functional groups attached to the compounds to be treated.